I hate to ride in as the Sacred Defender of Flavor-Text again, but if you have a 20th level hero with 120 hit points, he isn't getting hit by the "hits" those mooks with the .22's fire at him. He's getting slowed down by near misses, slowly losing his cool, slipping and banging his knee as a shot goes over his head, and so forth. Heck, maybe the shot tears across his expensive Mastercraft Sweater and leaves a thin and sexy line of blood or something as he twists to one side with preternatural awareness, trying to minimize the impact of the shot.
But nowhere in the d20 Modern book does it say that a guy with 120 hit points can just stand there and "Take the shot" because they know they have a lot of hit points. Voluntarily letting yourself get shot in the chest is CdG territory.
As far as the realism/cinematicness goes, I ran some fights with my players to get them used to the new level of d20 Modern relative to D&D. One guy got taken down in a single shot -- he was a 10th level all-physical-classes character. d20 Modern Fort saves do NOT go up so quickly that Massive Damage checks are trivial. As somebody with little real-world experience with guns, I have no problem with how autofire works (aside from wishing that it was slowed down by armor, but really, that's part of the armor-as-DR desire). And having to be killed by SEVERAL shots from a .22 is no worse than having to die from SEVERAL stab wounds with a knife.
The biggest problem that I see with d20 Modern is that you are really not very good at many things unless you sink feats/ranks/abilities into them. As somebody who is darn good with my empty hands but absolutely useless with a gun, even after a few lessons, I really have no problem with that -- but I think that a lot of D&D folks think that d20 Modern should have a higher standard of ability for someone who doesn't put any special emphasis into their training with something.
For example, .22's aren't lethal on their own. If I, Tacky, were wielding a .22, I doubt that I'd kill anyone except by dumb luck -- at least, not with a single shot. However, if a gun expert who had trained with light pistols took the same gun, he could probably take down people with one shot apiece without any real difficulty (of course, if we were ever attacked by giant bricks and boards, my karate-skills would have me chopping through them while his gun was useless, USELESS I TELL YOU, HAHAHAHA!).
My point is that I don't think that complaining about the .22 based on a guy with nothing more than Personal Firearms Proficiency is kind of silly. Let's see if someone who trains a LOT with the gun, if someone who makes it his life's work to get good with that gun, can do well with it.
Strong3/Soldier10 -- he can be a soldier, a mercenary, or a criminal enforcer.
Say Dex 16 -- not unreasonable after point-buy and level increases.
+10 BAB
+3 Dex
+1 Weapon Focus
+1 Point Blank Shot (assuming he has this feat, if he's such a gun-nut)
+15 on his normal attacks, with a non-mastercraft .22.
Damage: 2d4+4 (+1 inside 30'), 19-20 crit
On a hit inside 30', he does an average of 10 points damage. He can do as much as 13.
On a 19 or 20, he crits without having to confirm. Assuming a 19 hits, he has a 10% chance to do 100% more damage. So if he's attacking another human, his hits do an average of 11 (counting crits) and can do as much as 26 on a crit.
That's without double-tap, which lets him take a penalty and add an average of 2.5 points of damage to his hit. You could build a similar sort of character using Gunslinger classes -- in which case you sacrifice the Specialization damage but gains the potential "Bullseye" damage (+3d6 damage if you spend an action point).
So that fellow, in either of his incarnations, could make the .22 a reasonably dangerous weapon -- doing more damage because of the accuracy of his shots.
